Hydrogenation of hydrocarbons



Patented July 9, 1935 HYDROGENATION F HYDROCARBONS Antoni Szayna, Lwow,Poland, assignor to Sinclair Refining Company, New York, N. Y., acorporation of Maine Application June 6, 1931, Serial No. 542,581Renewed May 7, 1935 2 Claims.

This invention relates to improvements in the manufacture of lowerboiling oils such as gasoline by cracking and hydrogenating higherboiling oils, such as kerosene and gas oil and heavier oil,

5 without a. catalyst.

When higher boiling oils are heated to a cracking temperature theproducts of the consequent reaction include hydrocarbons relatively poorin hydrogen which tend to polymerize to form "coke or solid or semisolidpitches. The presence of hydrogen in concentration suiiicient to exertmore than a characteristic minimum partial pressure tends to inhibitsuch polymerization and formation of coke and pitches. To be eiective inthis respect, however, it is not suiiicient that the hydrogen begenerally present in the region of reaction. It must be immediatelypresent, with respect both to time and to place, as the constituentmolecules of the higherboiling oil decompose or crack. For this reasonthe uniform progress of the combined reaction depends to an importantextent upon the maintenance throughout the region of reaction of acontinuously uniform intimate mixture or dispersion of the hydrogen inthe oil.

'I'he conventional apparatus for supplying higher boiling oil andhydrogen to such operations includes, because of the high pressuresusually employed, pumps or compressors of reciprocating type. Eventhough extreme mechanical precautions be taken, there is an ever presenttendency toward the development of successive fluctuations in themomentary hydrogen concentration in a composite stream formed by mergingthe discharge, for example, of an oil stream from such a pump and ahydrogen stream from such a compressor. Thus, even though there besuflicient hydrogen in the system generally to avoid the formation ofcoke or pitches, coke or pitches will frequently form in a system sooperated because the cracking of the oil proceeds irrespective of thehydrogen concentration with consequent polymerization and formation ofcoke or pitches wherever the hydrogen concentration is deficient.Operating without a catalyst, such coke or pitches do not react toproduce desirable products but are either deposited in the system ordischarged from the system as coke or pitch.

According to the present invention higher boiling oil and hydrogen areforced to the heating zone, in which the combined cracking andhydrogenating operations proper are carried out, a heating coil arrangedin a heating furnace for example, through a receptacle adapted tocontain a substantial body of a mixture of the two and a substantialbody of the mixture is maintained in this receptacle. 'I'his body of themixture is maintained at a temperature below that at which substantialcracking of the oil begins and eiective dispersion of the hydrogen inthe oil is maintained throughout this body. This receptacleadvantageously is proportioned to contain a volume of the mixtureexceeding, best several times, the single stroke displacement of anyreciprocating hydrogen compressor used plus the volume of oilcorresponding on the basis of the proportions of the average mixturesupplied to the heating zone. This receptacle through which the mixturepasses from the forcing means to the heating zone, in accordance withthe invention, thus constitutes a reservoir in which momentaryvariations of hydrogen concentration are reduced to a Since the oil ismaintained at a temperature below that at which substantial crackingbegins in this receptacle, momentary variations in the hydrogenconcentration are reduced to a minimum before cracking of the oilbegins. The mixture of higher boiling oil and hydrogen supplied to theheating zone from this receptacle is not only intimate but alsocontinuously uniform, or very nearly so, so that optimum conditions withrespect to hydrogen concentration and dispersion are maintained from atemperature below that at which substantial cracking of the oil begins.Due to the maintenance of these optimum conditions, the combinedcracking and hydrogenating operation may be carried out under somewhatlower pressures.

The invention provides for the production of a maximum of gasoline withthe formation of but a minimum, if any, of coke or pitches and for themost effective use of the hydrogen supplied to the operation, without acatalyst.

The accompanying drawing illustrates, diagrammatically andconventionally, one form of apparatus adapted for carrying out theprocess of the invention, Fig. 1 being an elevation partly in sectionand with parts broken away and Fig. 2 being a fragmentary section facingthe small end of receptacle 8.

The apparatus illustrated comprises a pump I and a compressor 2 forsupplying oil and hydrogen, respectively, to the heating coil 3 arrangedin the heating furnace 4 through a receptacle 8. In the apparatusillustrated the products of the cracking and hydrogenating operationcarried out in the heating coil 3 are discharged through the coolingcoil 5 to the separator 6. To prolong the period of time at which thereacting materials are maintained at high temperature under highpressure, a thermally insulated digestor may be interposed in theconnection between the heating coil 3 and the cooling coil 5. Instead ofdischarging the hot mixture from the heating coil, or the digestor,through the cooling coil, it may be discharged, with reduction ofpressure, into a fractionating system in which it may be fractionatedinto a residual fraction and one or more distilled fractions by itscontained heat. The fan 1 is provided for recirculating over the heatingcoil 3, together with fresh hot products of combustion from the firebox, a part, advantageously a large part, of the heating gases whichhave passed over the heating coil 3, to assist in the maintenance ofuniform conditions.

The mixture of oil and hydrogen may be heated to a temperature in therange, for example, of 80G-950 F. under a pressure in the range, forexample, of 50-300 atmospheres in the heating coil 3. Hydrogenconcentrations in the range, for example, of 0.5 4.0%, or better 1-3%,by weight on the oil may be used.

The apparatus illustrated includes a particularly advantageous form ofthe receptacle to be interposed between the forcing means and theheating zone in accordance with the invention. This receptacle isconical in shape. The mixture of oil and hydrogen supplied from thereceptacle to the heating zone is discharged through the small end ofthe cone, through connection 9. The oil and hydrogen are supplied to thelarge end of the cone through connections I and Il, respectively,arranged to discharge into the receptacle tangentially with respect tothe cone. The point of oil introduction is advantageously spaced towardthe small end of the cone from the point of hydrogen introduction. Bymeans of this arrangement, internal moving parts may be eliminated. Areceptacle provided with internal mechanical dispersing means, forexample, may however be substituted for the form illustrated.

I claim:

1. In the manufacture of lower boiling oils by cracking andhydrogenating higher boiling oils without a catalyst, the improvementwhich comprises, forcing all the higher boiling oil and hydrogen passingto a heating zone through a receptacle adapted to contain a substantialbody of the mixture and thereby maintaining a substantial body of themixture in said receptacle, maintaining said body of the mixture at atemperature below that at which substantial cracking of the oil begins,maintaining effective dispersion of the hydrogen in the oil in saidreceptacle, heating the mixture to a cracking temperature under apressure upwards of 50 atmospheres in said heating zone and maintaininga continuously uniform intimate dispersion of the hydrogen in the oilthroughout the region of reaction.

2. -In the manufacture of lower boiling oils by cracking andhydrogenating higher boiling oils without a catalyst, the improvementwhich comprises, forcing all the higher boiling oil and hydrogen passingto a heating zone through a receptacle adapted to contain a substantialbody of the mixture and thereby maintaining a substantial body of themixture in said receptacle, maintaining said body of the mixture at atemperature below about 650 F., maintaining effective dispersion of thehydrogen in the oil in said receptacle, heating the mixture to acracking temperature upwards of about 800 F. under a pressure upwards of50 atmospheres in said heating zone and maintaining a continuouslyuniform intimate dispersion of the hydrogen in the oil throughout theregion of reaction.

ANTONI SZAYNA.

